Semi Bolt Receiver Assembly for assembly with a Semi Automatic Rifle Base

ABSTRACT

A new and useful a semi bolt receiver assembly is provided, that configured for assembly with a rifle base that has a buttstock and pistol grip configured for semi automatic operation. The semi bolt receiver assembly includes a receiver, a bolt and carrier assembly, and a manually operable handle that is coupled with the bolt and carrier assembly in a manner that enables the bolt and carrier assembly to be manipulated by a shooter to charge the rifle (i) while the shooter is maintaining a shooting position and (ii) without removing the shooter&#39;s hand from the pistol grip. The semi bolt receiver assembly is particularly useful when configured for assembly with an AR-15 rifle base.

Related Application/Claim of Priority

This application is related to and claims priority from U.S. provisionalapplication Ser. No. 61/276,629, filed Sep. 15, 2009, entitled “Semibolt action conversion adaptor for AR 15 rifle” which provisionalapplication is incorporated herein by reference

INTRODUCTION, BACKGROUND AND SUMMARY OF THE PRESENT INVENTION

The present invention relates to a new and useful structure, referred toherein as a “semi bolt receiver assembly” that is designed to be coupledwith semi automatic rifle base, e.g. the lower portion (also referred toas a lower receiver) of a rifle of the modular type which is well knownin connection with a rifle known as the AR 15. The type of semiautomatic rifle base with which the semi bolt receiver assembly of thepresent invention is particularly useful would typically comprise abuttstock and pistol grip configured for semi automatic operation, suchthat the buttstock has a buffer spring that is compressed by movement ofa bolt and carrier assembly against a buffer when the rifle is beingdischarged or unloading a spent round and causes the buffer to act on abolt carrier assembly (e.g. in the manner of a semi automatic rifle)when the rifle is being charged or loaded.

The principles of the present invention are described herein inconnection with conversion of a semi automatic rifle base (e.g. an AR15semi automatic rifle base) to semi bolt-action operation with theapparatus described herein, and from that description the manner inwhich the principles of the present invention can be used to convertsimilar types of rifle base, (e.g. AR 10 or SR 25 rifles) or create newrifles in accordance with those principles, will be apparent to those inthe art. In addition, the principles of the present invention areparticularly useful to produce an upper receiver assembly that can beassembled with a rifle based that is substantially conformable to thestandards of existing AR 15/M16 rifle lower receivers.

In applying the principles of the present invention to a semi automaticrifle base such as an AR 15 rifle, the purpose of the inventionincludes:

1) improving the accuracy of the rifle by converting the gas operatingsystem to manual operation;

2) retaining a cartridge loading speed advantage over convention boltaction rifles;

3) eliminating the action fouling due to the gas operating system of thesemi automatic AR 15 rifle; and

4) improving the ability to manipulate the bolt with the least movementand effort.

The AR15 Rifle is one of the most versatile and affordable rifle designsever conceived and certainly the most modified and adapted beyond itsintended military use. In recent years it has become the most widelyused target rifle in certain competitive disciplines and new dedicatedvariants appear frequently.

The rifle is divided into an upper and lower half (Exhibits A1, A2). Thelower half, connects to a buttstock, and contains the pistol grip, thetrigger mechanism and holds the ammunition. It is the registered part ofthe rifle. The upper half, to which this invention pertains, containsthe bolt and carrier assembly, the barrel, sights and special purposeattachments. It can be configured in many ways. Because of its modulardesign it is possible to have one lower half and many different upperhalves (sometimes called variants) each dedicated to a different type ofshooting or purpose because each will mate to the lower half. Theinvention proposed herein was inspired primarily by a desire to improvethe performance of the rifle in the target shooting disciplines butshould have diverse appeal. It should be considered a new variantbecause it has a dedicated design and function that is distinctlydifferent from any existing variants or any known rifles known toapplicant.

If the AR15 Rifle has a drawback, in the sport of target shooting, it isthe gas operated self-loading system that employs parts that move duringthe shot process. It is an undesirable characteristic that can affectaccuracy and many top competitors prefer to use a traditional orspecialized bolt action rifles in long-range events, bench restcompetition, or varmint hunting; all of which demand extreme accuracy.The bolt-action rifle operates with a closed bolt throughout the firingprocess and causes no disturbance to the rifle when it is fired.However, despite having an edge in accuracy the bolt action rifle hasits own drawbacks. For example, in NRA “Match Rifle” competition thereare two separate rapid-fire stages in the match that are conducted atdifferent ranges and from different positions. Many shooters havedifficulty firing all the required shots accurately due to the time ittakes to manually operate the bolt; which must be raised to unlock thebolt, pulled to extract the spent cartridge, pushed in order to extracta cartridge from the magazine and chamber it, and lowered in order tolock the bolt. Sometimes the shooter must raise his head off the stockto avoid the retracting bolt. In the prone position it is sometimesnecessary to lift ones arm from the shooting mat, in order to operatethe bolt. The more expensive bolt action competition rifles incorporatefeatures designed to overcome these drawbacks (in a manner differentthan the present invention) but most shooters cannot afford them. All ofthese circumstances cause the “position” of the shooter to break down.At these short and middle range events, which are fired at 200 to 300yards the self-loading AR15 rifle enjoys an advantage because theshooter does not have to manipulate a bolt. The same rifle must be usedacross the entire course of fire.

When the match moves back to the 600-yard slow fire stage thebolt-action rifle assumes an advantage because there are no moving partsduring the shot process. The scores at this stage generally determinethe winner of the match. With the recent offering of improved cartridgesand calibers for the AR15 the bolt-action does not enjoy the completedominance that it once had at long range, but it is often preferred.

The invention described herein seeks to address the issue of accuracyand retain most of the speed advantage enjoyed by the AR15 with a semibolt-action configuration. It also has the added benefit of a muchcleaner action with less wear and requires less lubrication andmaintenance by way of eliminating the gas operating system which foulsthe action. It also makes it ergonomically feasible to shoot accuratelyin timed shooting events that, until now, have been impractical withother conversions. The application is intended primarily for rifles thatwould normally employ an AR15 A3 style flattop upper receiver whichoften requires the use of a scope, as in bench rest shooting, orsophisticated iron sights as in NRA Match Rifle competition. It willeasily adapt to other disciplines as well.

In accordance with the present invention, a semi bolt receiver assemblyis configured for assembly with a rifle base that has a buttstock andpistol grip configured for semi automatic operation. The semi boltreceiver assembly includes a bolt and carrier assembly, and a manuallyoperable handle is coupled with the bolt and carrier assembly in amanner that enables the bolt and carrier assembly to be manipulated by ashooter to charge the rifle (i) while the shooter is maintaining ashooting position and (ii) without removing the shooter's hand from thepistol grip. Preferably, the handle and bolt and carrier assembly arecoupled and configured in a manner that enables the operation of themanually operable handle in charging the rifle to be substantially astraight pull action, while the shooter is maintaining an undisturbedshooting position.

The concept of a rifle base that is configured for semi automaticoperation means that the rifle base has an attached buttstock and pistolgrip configured for semi automatic operation means, in that thebuttstock has a buffer spring that is compressed when the rifle is beingdischarged or unloaded and acts on a buffer to move the bolt carrierassembly in the manner of a semi automatic rifle when the rifle is beingcharged or loaded.

In a preferred embodiment, the manually operable handle is coupled withan adaptor base in a manner that enables the length of pull of theadjustable handle to be selectively adjusted over a predetermined range.In addition, the handle is coupled with the adaptor base in a mannerthat the handle extends at an angle to the bolt and carrier assembly andallows the handle to be selectively manipulated to adjust the angle atwhich the handle is oriented relative to the bolt and carrier assembly.The connection between the handle and the bolt and carrier assembly ispreferably configured in a manner that enables the operation of themanually operable handle in charging the rifle to be substantially astraight pull action by a shooter, along a side of the receiver, in aconvenient orientation to be grasped by a shooter's hand on that side ofthe receiver.

Also, the bolt and carrier assembly includes a bolt carrier with asubstantially cylindrical configuration, and the adaptor base isconnected with the bolt carrier by one or more fasteners that extendfrom the adaptor base through the top of the cylindrical bolt carrierand directs forces applied to the fastener from the top of thecylindrical bolt carrier downward along a line of action extendingthrough the center of the cylindrical bolt carrier. Thus, the line ofaction of forces on the bolt and carrier assembly is through arelatively strong section of the bolt and carrier assembly, which isdesigned to minimize the risk of breakage of components when the rifleis being manipulated and fired.

Thus, a rifle with a semi bolt receiver assembly configured according tothe principles of the present invention, is designed to enable a shooterto recharge the bolt and carrier assembly while maintaining a shootingposition and without removing the shooter's hand from the pistol grip.This enables the shooter to have the accuracy normally provided by abolt action rifle, and the speed of firing that is normally associatedwith a semi automatic rifle such as the AR 15. The principles of thepresent invention are particularly useful in configuring a semi boltreceiver assembly that can be assembled with a rifle base or lowerreceiver that is substantially conformable to the standards of existingAR15/M16 rifles.

These and other features of the present invention will become furtherapparent from the following detailed description, and the accompanyingdrawings and exhibits.

Brief Description of the Drawings and Exhibits

FIG. 1 is a schematic illustration of a shooter in a firing positionwith a rifle having semi bolt receiver assembly, according to theprinciples of the present invention;

FIG. 2 is an enlarged, schematic illustration of a portion of the riflehaving the semi bolt receiver assembly according to the principles ofthe present invention;

FIG. 3 is an exploded view of components forming the semi bolt receiverassembly, according to the principles of the present invention;

FIG. 4 is a schematic illustration of the semi bolt receiver assemblyaccording to the principles of the present invention, in one of itsoperational positions;

FIG. 5 is a side view of a modified configuration of an adaptor base,handle and handle mount, for a semi bolt receiver assembly, according tothe principles of the present invention;

FIG. 6 is a top view of the modified configuration of FIG. 5;

FIG. 7 is a side view of a portion of the receiver, for the modifiedconfiguration of FIG. 5; and

FIG. 8 is a rear view of the modified configuration of FIG. 5.

Exhibit A1 is an exploded view of the primary components of an AR 15rifle, Exhibit A2 is a detailed exploded view, and parts list for an AR15 rifle, Exhibit A3 illustrates how when the principles of the presentinvention are used to modify an existing AR 15 rifle, the adaptor baseof the present invention prevents the bolt from closing if the gas tubeof the AR 15 is not removed, and

Exhibits B-D are views of a shooter operating a rifle with an AR 15rifle base, and a semi bolt receiver assembly configured according tothe principles of the present invention.

DETAILED DESCRIPTION

As described above, the present invention relates to a new and usefulstructure, referred to herein as a “semi bolt receiver assembly” that isdesigned to be coupled with a modular type rifle base, which is wellknown in connection with a rifle known as the AR 15. In a typical AR 15rifle, the primary components are a magazine 1, bolt carrier assembly 3,charging handle 4, upper receiver and barrel assembly 5, and lowerreceiver and buttstock assembly 6 (see Exhibit A1). The semi boltreceiver assembly of the present invention would replace the upperreceiver and barrel assembly. The coupling between the semi boltreceiver assembly of the present invention and the lower receiver andbuttstock assembly 6 would typically comprise takedown or pivot pinsthat are shown at 77 and 61 in Exhibit A2.

The principles of the present invention are described herein inconnection with conversion of a typical AR15 semi automatic rifle tosemi bolt-action operation with the semi bolt receiver assemblydescribed herein. Also, Exhibit A2 shows an exploded view and parts listfor an AR 15 rifle, and wherever possible in this description, where acomponent that is described herein is essentially the same as the partof Exhibit A1 or Exhibit A2, applicant has sought to retain thenumbering scheme of Exhibits A1 and A2. Where a component is either notshown in Exhibits A1 or A2, or is different from a component of thoseexhibits, on account of that component being configured in accordancewith the principles of the present invention, applicant has adopted anumbering scheme different from the parts lists of Exhibits A1 and A2.In addition, in the course of this detailed description, applicant hasdescribed existing rifles known to applicant and the manner in which arifle with the applicant's semi bolt receiver assembly both differs fromthose existing rifles, and is also believed to provide advantages inrelation to those rifles. From that description the manner in which theprinciples of the present invention can be used to convert riflessimilar to the AR 15, or create new rifles in accordance with thoseprinciples, will be apparent to those in the art.

According to the present invention a semi bolt receiver assembly 100(FIG. 3) is configured for assembly with a rifle base 102 that has abuttstock 104 (of conventional design as shown as part of the lowerreceiver and Buttstock assembly 6 shown in Exhibit A1) and pistol grip74 (also of conventional design, see e.g. Exhibit A2). The rifle base102 has a trigger 65, a buffer spring 41 and a buffer 42 (piston), thatare of conventional design (see e.g. Exhibit A2) and is configured forsemi automatic operation, in the sense that when the rifle discharges aspent cartridge, by pulling the charging handle that is describedherein, the buffer spring 41 is compressed, and when the charging handle120 (described further herein) is released, the buffer spring 41 causesthe buffer 42 to act on a bolt and carrier assembly (comprising acarrier 31 and a bolt 33, as shown in Exhibit A2), to strip and(schematically shown in FIG. 4), and insert a new cartridge from amagazine (shown at 1 in Exhibit A1).

According to the principles of the present invention, the semi boltreceiver assembly 100 has a manually operable handle 120 that is coupledwith the bolt and carrier assembly, in a manner that enables the boltand carrier assembly to be manipulated by a shooter to charge the rifle(i) while the shooter is maintaining a shooting position and (ii)without removing the shooter's hand from the pistol grip 74. The boltand carrier assembly is of a conventional configuration, e.g. comprisinga bolt carrier 31 and bolt 33 as shown in Exhibit A2 and in the Figures.The handle 120 is coupled with the bolt carrier assembly, in a mannerdescribed herein, such that the operation of the manually operablehandle 120 in charging the rifle is a substantially a straight pullaction, while the shooter is maintaining a shooting position.

Thus, as seen in FIG. 1, and in Exhibits B-D, a shooter is holding arifle with a semi automatic base (e.g. comprising Buttstock 104, trigger65 and pistol grip 74) and a semi bolt receiver assembly 100 accordingto the principles of the present invention. In Exhibit B, the shooter issqueezing the trigger to fire the rifle. In Exhibit C, the shooter ispulling the handle 120 to discharge a spent cartridge from the rifle,and as shown in Exhibit C, as the shooter is pulling the handle, theshooter's hand remains on the pistol grip 74. In Exhibit D, the shooterhas released the handle 120, but (although not shown) the shooter'sthumb remains about the pistol grip 74. As the handle 120 is released,the buffer spring 41 causes the buffer 42 to act on the bolt and carrierassembly to strip (see FIG. 4) and load (insert) a new cartridge fromthe magazine (1 in Exhibit A1) into the rifle chamber, in position to befired. Thus, as will be appreciated by those in the art, the rifleaccording to the present invention provides the bolt action as thehandle is pulled, is like a bolt action rifle in that there is nodiversion of combustion gas when the rifle is fired and has the semiautomatic rifle feature of utilizing the buffer spring 41 and buffer 42to act on the bolt and carrier assembly when the handle 120 is released,to strip and insert a new cartridge, in the manner of a semi automaticrifle.

In the semi bolt receiver assembly 100 of the present invention, themanually operable handle 120 is coupled with a handle mount 122 that hasa portion which extends through a side opening 123 in a web portion 125of a receiver 101 that forms part of the semi bolt receiver assembly100. The height H of that portion of the receiver 101 that includes theweb 125 is preferably at least 2.25 inches (see FIG. 7), to enable thehandle 120 to be supported in the manner described further herein, andto be located in a convenient manner to enable a shooter to operate therifle in the manner illustrated in Exhibits B-D.

When the semi bolt receiver assembly 100 is configured by modifying anexisting AR 15 type upper half, the semi bolt receiver assembly isconfigured to restrict diversion of a portion of combustion gas that isgenerated when the rifle is being fired. This can be done, e.g. byproviding a barrel band 124 (FIG. 1) that covers the gas diversion portin the AR 15 rifle barrel (and also by removing the gas tube 4 (ExhibitA2), because the adaptor base is configured such that in the presence ofa gas tube the bolt cannot close and the rifle cannot fired, so that thegas tube shown at 4 in Exhibit A2 must be removed, as will be furtherappreciated from Exhibit A3). On the other hand, if a receiver assemblyis configured to operate according to the principles of for the presentinvention, rather than modifying an existing AR 15 type receiver, thesemi bolt receiver assembly shown in FIG. 1 would have a barrel that isconfigured without a gas port for diverting a portion of combustion gasthat is generated when the rifle is being fired.

In assembling a semi bolt receiver assembly 100, according to theprinciples of the present invention, an adaptor base 130 is coupled withthe bolt and carrier assembly, which are contained by the semiboltreceiver 101, and the handle mount 122 (to which the handle 120 iscoupled) is connected to the adaptor base. Specifically, the handlemount 122 includes a sleeve 122 a that is fixed to a coupling portion122 b which, in turn is fastened to the adaptor base 130 (e.g. by one ormore cap head screws that extend through openings 127 in the adaptorbase). The adaptor base 130 is coupled to the bolt carrier 31, and theadjustable handle 120 is coupled with the handle mount 122 in a mannerthat enables the length of pull of the adjustable handle 120 to beselectively adjusted over a predetermined range. Also, adjustable handle120 is coupled with the handle mount 122 in a manner that enables thehandle to be selectively manipulated relative to the connection portionto adjust the angle at which the handle is oriented relative to the sideof the semi bolt receiver 100. It should also be noted that the receiverassembly may have a pair of sights 140, 142 that would be ofconventional design, where the sight 140 may be connected to a weaverrail 144 that would also be of conventional design.

Specifically, the handle 120 comprises a relatively straight portion 120a, and a portion 120 b that extends at an angle to the straight portion120 a. The straight portion 120 a is received in the sleeve 122 a of thehandle mount in a manner that enables the handle to slide relative tothe handle mount and to rotate (pivot) in the sleeve 122 a. The handlecan be locked in a selected position for adjusting the pull length ofthe handle, by a set screw 136 and can be locked in a selectedrotational (angular) orientation by a clamp nut 138 that can betightened about the handle portion 120 a. This allows both the length ofpull of the handle, and the angular orientation of the handle relativeto the receiver 101 to be selectively adjusted. In addition the handlehas a knob 120 c that is adjustable for height in order to accommodatehand size and individual style of gripping the rifle (see e.g. FIG. 8).

In another aspect of the present invention, the bolt carrier 31 has asubstantially cylindrical configuration (as is known), and the adaptorbase 130 is connected with the bolt carrier by one or more fasteners 141(see FIGS. 3 and 8), each of which extends through the adaptor base andinto the top of the cylindrical bolt carrier 31. Thus, forces applied tothe adaptor base 130 are directed through the cylindrical bolt carrierare along a line of action extending through the center of thecylindrical bolt carrier 31. In essence, as those in the art willappreciate, the adaptor base 130 is coupled to the bolt carrier in amanner that it replaces the bolt carrier key 28 of the conventional boltcarrier assembly of Exhibit A2. That enables the adaptor base 130 to becoupled to the bolt carrier at a relatively strong location, and tochannel forces applied from the handle along a line of action that issubstantially downward along a line of action through the center of thecylindrical bolt carrier 31. Such a coupling is designed to minimize therisk of the connection between the handle 120 and the bolt carrierassembly from breaking or becoming deformed as the handle is beingrepeatedly operated.

Thus, as will also be appreciated by those in the art, with a semi boltreceiver assembly according to the present invention, assembled withrifle base that has a buttstock and pistol grip configured for semiautomatic operation, the connection between the handle and the bolt andcarrier assembly enables the orientation of the handle relative to thebolt and carrier assembly to be selectively adjusted to a plurality ofoperating orientations relative to the bolt and carrier assembly and ina manner that enables the handle to charge the bolt and carrier assemblywhen the handle is in any of the plurality of operating orientations.The connection between the handle and the bolt and carrier assembly isdesigned to enable the shooter to charge the rifle with a straight pullaction, and without removing the shooter's hand from the pistol grip ofthe rifle. This enables relatively rapid firing of the rifle, in amanner that is like that of a semi automatic rifle, but avoids thevarious issues that are described herein that result from the diversionof combustion gas that is associated with operation of a semi automaticrifle.

In the modification shown in FIGS. 5-8, the adaptor base 130 has aslightly different configuration than that shown and described in FIG.3, but retains the features described above, in terms of providing arelatively strong coupling between the handle 120 and the bolt andcarrier assembly, and in providing for adjustment of the pull length ofthe handle and the angular position of the handle. In addition, FIG. 7illustrates the added height of the receiver 101, in the extended webarea 125 that accommodates the slot 123 for the handle, and the mannerin which that added height is used to provide the handle in a convenientoperating position, in accordance with the principles of the presentinvention. Specifically, as shown in FIG. 7, the added height of thereceiver 101 is provided in the web portion 125 that adds about ½ inchto the overall height of the receiver 101 (compared to a standard A3receiver), so that the receiver 101 is at least about 2.25 inches inoverall height. That added web portion carries the slot 123, and thehandle mount 122 has a portion 122 c extends through that slot, so thatthe handle mount sleeve 122 a into which the handle portion 120 a fitsis located on a side of the receiver 100, and the handle portion 120 bextends angularly downward relative to the receiver at a convenientangle to be grasped by a shooter and operated in the manner describedherein.

It is believed the following description will further enable those inthe art to appreciate the structure and operation of the semi boltreceiver assembly of the present invention.

The AR15 Rifle is one of the most versatile and affordable rifle designsever conceived and certainly the most modified and adapted beyond itsintended military use. In recent years it has become the most widelyused target rifle in certain competitive disciplines and new dedicatedvariants appear frequently.

The rifle is divided into an upper and lower half (Exhibits A1, A2). Thelower half contains the trigger mechanism and holds the ammunition. Itis the registered part of the rifle. The upper half, which thisinvention concerns, contains the bolt and carrier assembly, the barrel,sights and special purpose attachments. It can be configured in manyways. Because of its modular design it is possible to have one lowerhalf and many upper halves each dedicated to a different type ofshooting or purpose because each will mate to the lower half. Theinvention proposed herein was inspired primarily by a desire to improvethe performance of the rifle in the target shooting disciplines butshould have diverse appeal.

If the AR15 Rifle has a drawback, in the sport of target shooting, it isthe gas operated self-loading system that employs parts that move duringthe shot process. It is an undesirable characteristic that can affectaccuracy and many top competitors prefer to use a traditional orspecialized bolt action rifles in long-range events, bench restcompetition, or varmint hunting; all of which demand extreme accuracy.The bolt-action rifle operates with a closed bolt throughout the firingprocess and causes no disturbance to the rifle when it is fired.However, despite having an edge in accuracy the bolt action rifle hasits own drawbacks. For example, in NRA “Match Rifle” competition thereare two separate rapid-fire stages in the match that are conducted atdifferent ranges and from different positions. Many shooters havedifficulty firing all the required shots accurately due to the time ittakes to manually operate the bolt; which must be raised to unlock thebolt, pulled to extract the spent cartridge, pushed in order to extracta cartridge from the magazine and chamber it, and lowered in order tolock the bolt. Sometimes the shooter must raise his head off the stockto avoid the retracting bolt. In the prone position it is sometimesnecessary to lift ones arm from the shooting mat, in order to operatethe bolt. The more expensive bolt action competition rifles incorporatefeatures that overcome these drawbacks but most shooters cannot affordthem. All of these circumstances cause the “position” of the shooter tobreak down. At these short and middle range events, which are fired at200 to 300 yards the self-loading AR15 rifle enjoys an advantage becausethe shooter does not have to manipulate a bolt. The same rifle must beused across the entire course of fire.

When the match moves back to the 600-yard slow fire stage thebolt-action rifle assumes an advantage because there are no moving partsduring the shot process. The scores at this stage generally determinethe winner of the match. With the recent offering of improved cartridgesand calibers for the AR15 the bolt-action does not enjoy the completedominance that it once had at long range, but it is often preferred.

The invention described herein seeks to address the issue of accuracyand retain most of the speed advantage enjoyed by the AR15 with a semibolt-action configuration. It also has the added benefit of a muchcleaner action with less wear and requires less lubrication andmaintenance by way of eliminating the gas operating system which foulsthe action. It also makes it ergonomically feasible to shoot accuratelyin timed shooting events that until now have been impractical with otherconversions. The application is intended primarily for rifles that wouldnormally employ an AR 15 A3 flattop upper receiver (Exhibits B-D) whichoften requires the use of a scope, as in bench rest shooting, orsophisticated iron sights as in NRA Match Rifle competition. It may beadaptable to other variants as well. The principles of the presentinvention are particularly useful in configuring a semi bolt receiverassembly that can be assembled with a rifle base or lower receiver thatis substantially conformable to the standards of existing AR15/M16rifles, as will be clear to those in the art.

When a shot is fired in an unmodified AR15 Rifle, gas pressure from thepropellant pushes the bullet down the barrel as in any other rifle. At apoint approximately two thirds of the way down the barrel is a small gasport manifold that bleeds off a small portion of combustion gas as thebullet passes the hole. This gas is partially expelled into the actionthrough a gas tube rearward to the rifle action where it enters thecarrier key that sits atop the bolt carrier. The carrier key (ExhibitA2) diverts the gas to the inside and back of the bolt recess Thecarrier acting as a barrier to the gas, is pushed rearward which, via acam pin, causes the bolt to unlock from the chamber and begin theextraction of the spent cartridge. When the bolt carrier has reached itsrearmost position the spent cartridge is ejected and gas is expelledinto the action. Simultaneously the bullet exits the barrel. The boltcarrier has compressed a buffer spring, located in the buttstock of therifle, which then pushes the bolt and carrier assembly forward. Acartridge is stripped from the magazine, is chambered, and the bolt isclosed via the bolt cam pin. The rifle is ready to fire again. It isthis movement of the bolt and carrier during the firing process thatleads to inaccuracy. It also leads to fouling of the action that isundesirable in any rifle much less one used for competition.

In a retrofit application the semi-bolt conversion is accomplished byfirst removing the gas tube and manifold and then covering the hole witha barrel band (see e.g. FIG. 1) that is secured to the barrel either bya setscrew or adhesive. This will prevent any gas from escaping exceptfrom the muzzle of the barrel. This operation is only necessary whenconverting existing barrels. New barrels can be manufactured without thegas port; thereby eliminating the need for the barrel band.

All the remaining steps are common to retrofit and new manufacture upperhalves. A newly designed, taller, upper receiver assembly (FIG. 7) isemployed in order to facilitate the use of a semi-bolt action adapterbase and side-charging handle (FIGS. 1-4, Exhibits B-D). Near the top ofthe receiver assembly a slot milled into the web under the sight rail,in order to accept the handle assembly which attaches to the base (FIG.7). The adapter base is composed of a mild steel block that is attachedby screws to the standard bolt carrier and replaces the carrier key andthe charging handle (shown at 4 in Exhibit A1). The side-charging handle120 of the present invention, which is adjustable, is attached to theadapter base, and is parallel to the side of the receiver. As a safetyfeature, the forward portion of the adapter base prevents the bolt fromclosing if a gas tube is present (see Exhibit A3), thereby requiringremoval of the gas tube when a receiver assembly according to thepresent invention is being retrofitted to an existing AR 15.

The operation of the rifle is much the same as before the modification.All safety features remain in place. When a cartridge is fired the boltremains closed without disturbing the rifle. The shooter extracts theround at his or her discretion by simply pulling back on the bolt handleto its rearmost position. The bolt cam pin rotates as before. The boltcarrier goes to the rear as before, the buffer spring is compressed, andthe spent cartridge is ejected. But no gas is expelled (diverted) duringthat action and it took about one second. To charge the rifle again onlyinvolves releasing the bolt handle. The buffer spring advances the boltand carrier, strips the cartridge from the magazine, chambers the roundand closes the bolt via the bolt cam (shown in Exhibit A2). The rifle isready to fire. The extraction, ejection, and charging of the rifle isaccomplished in a single motion. The shooter does not have to make fourseparate acts to operate the bolt. Neither did he have to remove hishand from the pistol grip of lift his elbow. Adjustability is essentialto facilitate the least movement of the firing hand which minimizesdeterioration of position. That is accomplished by the bolt handle whichis adjustable for length of pull, height, and angle. More time is gainedto reacquire the sight picture, sight alignment, and trigger controlthan is possible for bolt-action shooters in rapid-fire stages. Atlonger ranges, shooters benefit from the fact that the rifle undergoesno cycling induced movement during the shot due to the elimination ofthe gas operation of the bolt. All shooters will benefit from not havingto clean dirty deposits from their actions.

I have called it a semi-bolt action because after the conversion it isno longer a semi-automatic, but neither is it a true bolt-action.Properly speaking it would be, by default, a spring assisted straightpull action design. The straight pull action design has been around fornearly 100 years and was first widely employed in the Swiss K31 militaryrifle. Until the advent of semi-auto rifles the K31 straight pull riflewas the fastest manually loaded rifle available. It ejected the spentround and cocked the rifle on the rearward stroke and stripped a newround and chambered it on the forward stroke. Nearly all semi-auto andautomatic rifles employ some form of gas assisted extraction and springassisted loading variation of a straight pull design.

Other attempts to modify the AR15 to bolt action were primarily inspiredin Great Britain where semi-auto rifles are restricted. Competitiveshooters had to find ways to disable the self loading aspects of theirrifles in order to compete legally. Bradley Arms offers a “bolt action”AR15 for sale in the UK that employs a side charging handle whichattaches to the sidewall of the bolt carrier. In the U.S. variouscompanies have used this method in bolt action and semi-auto as well.All of them involve threading a stud of some sort into the sidewall ofthe bolt carrier and notching the receiver to some degree. Neither thereceivers or the bolt carriers were designed for this type ofmodification and there is a history of bolts and or studs breaking insome versions. Some of the receiver cuts are so extreme that it is hardto imagine they do not undermine the integrity of the receiver. All ofthem give the appearance of being an afterthought and most designs leavea hole where the original charging handle has been eliminated. (photo1).

Due to the bolt carrier being several inches above the pistol grip, andthe sidewall of the bolt carrier having only 3/16″ purchase, the side ofthe bolt carrier is a poor location for the kind of leverage and strainthat are introduced by the bolt handle. It was not intended for that.Some conversions appear to be attempting the same thing as the semi-boltdesign but cannot fully incorporate the vertical component of the bolthandle due to the extreme leverage against the bolt carrier. The shootercannot reach the handle without lifting the hand from the grip. Thesingle point attachment at the front of the bolt carrier, combined withthe long reach of the bolt handle, makes it impossible to have thesufficient vertical drop on the handle that would enable one tomanipulate the bolt without causing undue strain. It was necessary forme to address this problem early on in the testing of my own design andit led me to shy away from the obvious drawbacks of attaching to theside of the bolt carrier and skeletonizing the sidewall of the receiver.It became necessary to redesign the receiver in order to retain itsstrength and to take advantage of the existing mortise and mountingholes on the top of the bolt carrier that become available when the gaskey is removed. This method places the strain at the strongest part ofthe receiver; where it is contained by the web under the sight rail.This resulted in raising the sight rail by ½″ and had the added benefitof improving the sight picture for most shooters. In addition itprovided more height and surface area in order to resist rotationalleverage against the bolt carrier and maintain its proper alignment.

The semi-bolt method includes a built in safety feature that otherconversions do not. The base adapter is extended so that when it iscoupled with the bolt and carrier assembly, in the manner describedherein, in the presence of a gas tube the bolt cannot close and therifle cannot fire. The proposed receiver design contains no hole for thegas tube and the millwork to accommodate the original charging handlehas been eliminated. The semi-bolt system will not allow thesimultaneous use of gas system parts; specifically the gas carrier keyand the gas tube. Conversions which use a standard receiver and mount ahandle on the side of the carrier are capable of being reconverted tosemi auto. This causes a dangerous condition when a left handed personshoots a right handed gun that has a handle which extends to the rear.If an extended handle is present on a semi auto gun it is possible forthe shooter to be hit in the face by the handle. No such danger existswith the semi-bolt system because it is a dedicated single shot systemwith integral safety features which if removed will essentially disablethe gun.

Being that the AR15 is a modular platform very few specialized tools arerequired to build or modify a rifle. Many shooters prefer to build,rebarrel and modify their riffles themselves. For that reason retrofitkits could be offered to shooters and gunsmiths. These would include thereceiver, adapter base, a handle particular to the desired shootingdiscipline, and the barrel band to block the gas if necessary. Completeupper halves could be offered as well as complete rifles.

Commercially viability is almost certain. The proliferation of AR15variants in recent years continues unabated. A well thought out, userfriendly, bolt action would have appeal in several different aspects ofthe shooting sports. For example: a bolt action AR15 would overcome thestigma of it being a rifle suitable only for military use and targetshooting. There is a prejudice against semi-auto rifles being used forgame hunting because it is considered unsporting to shoot anything but abolt action. Some major firearms manufacturers have semi auto huntingvariants available but it is uncertain whether they have madesignificant inroads on the market. A bolt action AR15 upper might appealto those who already own an AR but hunt with traditional bolt actionrifles. An immediate niche would be found in Highpower Rifle competitionfor the reasons previously explained. In addition the improved utilityof the semi-bolt design will inspire many to upgrade their currentconversions to the new design.

The semi-bolt conversion enables one to dry fire practice sequentialfire stages of a match. Dry firing is a practice technique where theshooter, using dummy rounds, fires the gun in order to develop sightalignment, trigger control, position, and timing. Semi-auto shooterscannot dryfire practice the ten shot strings of a rapid fire because thedummy rounds cannot actuate the bolt cycle.

Already there exists in Great Britain a market for bolt action AR15rifles. In varmint hunting the AR is already very popular and would beeven more so if greater accuracy can be obtained. The same is true forbenchrest shooting where semi auto rifles are unable to compete at thechampionship level. The semi-bolt variant design would fill a longstanding void in the evolution of the AR15 rifle.

Thus, as seen from the foregoing detailed description, the presentinvention provides a new and useful concept that provides a semi boltaction receiver assembly that is configured for assembly with a semiautomatic rifle base, to retain the speed of operation of a semiautomatic rifle, while also provide the ease of operation and accuracyfeatures of a bolt action rifle. With the foregoing description in mind,it is submitted that the manner in which such genre of semi bolt actionreceiver assemblies can be produced, or retrofit to existing semiautomatic rifle bases, will be apparent to those in the art.

1. Apparatus comprising a semi bolt receiver assembly configured forassembly with a rifle base that has a buttstock and pistol gripconfigured for semi automatic operation, the semi bolt receiverincluding a bolt and carrier assembly, and a manually operable handle iscoupled with the bolt and carrier assembly in a manner that enables thebolt and carrier assembly to be manipulated by a shooter to charge therifle (i) while the shooter is maintaining a shooting position and (ii)without removing the shooter's hand from the pistol grip.
 2. Theapparatus of claim 1, wherein the handle and bolt and carrier assemblyare coupled and configured in a manner that enables the operation of themanually operable handle in charging the rifle to be substantially astraight pull action, while the shooter is maintaining a shootingposition.
 3. The apparatus of claim 2, wherein the semi bolt receiverassembly includes a receiver, and wherein the handle is coupled with ahandle mount that has a portion which extends through a side opening inthe receiver.
 4. The apparatus of claim 3, wherein the semi boltreceiver assembly is configured for assembly with an AR-15 rifle base.5. The apparatus of claim 4, wherein the semi bolt receiver assembly isconfigured to restrict diversion of a portion of combustion gas that isgenerated when the rifle is being fired.
 6. The apparatus of claim 4,wherein the semi bolt receiver assembly includes a barrel that isconfigured without a gas port for diverting a portion of combustion gasthat is generated when the rifle is being fired.
 7. The apparatus ofclaim 4, wherein the portion of the receiver assembly that has the sideopening has a height of at least 2.25 inches
 8. The apparatus of claim1, wherein an adaptor base is coupled with the bolt and carrierassembly, and the handle mount to which the handle is coupled isconnected to the adaptor base.
 9. The apparatus of claim 7, wherein theadaptor base is coupled to the bolt carrier, and the adjustable handleis coupled with the handle mount in a manner that enables the length ofpull of the adjustable handle to be selectively adjusted over apredetermined range.
 10. The apparatus of claim 8, wherein the semi boltreceiver assembly includes a receiver, and wherein the adjustable handleis coupled with the handle mount in a manner that enables the handle tobe selectively manipulated relative to the side of the semi boltreceiver to adjust the angle at which the handle is oriented relative tothe side of the semi bolt receiver.
 11. The apparatus of claim 10,wherein the semi bolt receiver assembly is configured for assembly withan AR-15 rifle base.
 12. The apparatus of claim 1, wherein the bolt andcarrier assembly includes a bolt carrier with a substantiallycylindrical configuration, and wherein the adaptor base is connectedwith the bolt carrier by one or more fasteners, each of which extendsthrough the adaptor base and into the top of the cylindrical boltcarrier and directs forces applied to the adaptor base through thecylindrical bolt carrier along a line of action extending through thecenter of the cylindrical bolt carrier.
 13. The apparatus of claim 12,wherein the semi bolt receiver assembly is configured for assembly withan AR-15 rifle base.
 14. Apparatus comprising a semi bolt receiverassembly configured for assembly with a rifle base that has a buttstockand pistol grip configured for semi automatic operation, the semi boltreceiver assembly including a. a bolt and carrier assembly, b. anadaptor base that is connected with the bolt and carrier assembly, c. amanually operable handle that is coupled with the adaptor base in amanner that enables the orientation of the handle relative to the boltand carrier assembly to be selectively adjusted to a plurality ofoperating orientations relative to the bolt and carrier assembly and ina manner that enables the handle to charge the bolt and carrier assemblywhen the handle is in any of the plurality of operating orientations,and d. a semi bolt receiver.
 15. The apparatus of claim 14, wherein thebolt and carrier assembly includes a bolt carrier with a substantiallycylindrical configuration, and wherein the adaptor base is connectedwith the bolt carrier by a fastener that extends from the adaptor basedthrough the top of the cylindrical bolt carrier and directs forcesapplied to the adaptor base through the cylindrical bolt carrier along aline of action extending through the center of the cylindrical boltcarrier.
 16. The apparatus of claim 15, wherein the manually operablehandle is connected to a handle mount that is coupled to the adaptorbase, the connection between the handle and the handle mount configuredto enable the length of pull of the adjustable handle to be selectivelyadjusted over a predetermined range.
 17. The apparatus of claim 16,wherein the handle has a connector portion that extends through and issupported in a sleeve that forms part of the handle mount, and thehandle has a hand grip portion that extends at an angle to the connectorportion, and wherein connector portion can be selectively connected atdifferent locations along the sleeve, and at selected rotationalorientations in the sleeve, to selectively adjust the length of pull ofthe handle, to selectively adjust the angle at which the hand grip isoriented relative to the bolt and carrier assembly.
 18. The apparatus ofclaim 17, wherein the handle and bolt and carrier assembly are coupledand configured in a manner that enables the operation of the manuallyoperable handle in charging the rifle to be substantially a straightpull action.
 19. The apparatus of claim 18, wherein the semi boltreceiver has a side slot, through which a portion of the handle mountcarrying the sleeve extends, so that the handle is located on a side ofthe receiver, in a convenient orientation to be grasped by a shooter'shand on that side of the receiver.
 20. The apparatus of claim 15,wherein the semi bolt receiver is configured for assembly with an AR-15rifle base, and the portion of the receiver carrying the side slot has aheight of at least 2.25 inches